Part 2 BMB 555

Condensins

assemble into complexes on the DNA when phosphorylated by M-Cdk

Meiosis involves a single round of DNA replication followed by two successive cell divisions.

True

Organisms that reproduce sexually

undergo a sexual reproductivw cycle that involves an alternation Of haploid cells with the generation of diploid cells

A diploid cell containing 32 chromosomes will make a haploid cell containing ___ chromosomes.

16

Loss of function mutations

Are usually recessive

kinetochores

Assemble onto chromosomes during late prophase

The retinoblastoma (Rb) protein blocks cells from entering the cell cycle by

Inhibiting the transcription of genes required for entry into S phase

The G1 DNA damage chekcpoint

Involves the stabilization of p53 and the inhibition of cyclin-Cdk complexes by p21

How does S cdk help guarantee that replication occurs only once during each cell cycle?

It phosphorylated and inactivated Cdc6 and the ORC

You create cells with a version of the origin recognition complex, ORC, that cannot be phosphorylated by S-Cdk and thus cannot be inactivated. Which of the following statements describes the likely consequence of this change in ORC? (a) Cells will enter S phase prematurely. (b) Cells will replicate some regions of the genome more than once in a cell cycle. (c) The origin recognition complex (ORC) will be unable to bind to DNA. (d) DNA helicases will not be able to open up the double helix at the replication origin.

B

The principal microtubule organizing center in animal cells is the

Centrosome

At the end of DNA replication, the sister chromatids are held together by the

Cohesins

A cells that is terminally differentiated will

Dismantle the cell cycle control system

All traits that Mendel studied were dominant

False

Cdc25 dephosphorylation of Wee1 activates the kinase, promoting the G2/M transition. TRUE or FALSE?

False

Mutations in somatic cells are passed on to individuals of the next generation

False

Once a cell decides to enter the cell cycle, the time from start to finish is the same in all eukaryotic cells. TRUE or FALSE

False

The anaphase-promoting complex (APC) is continuously active throughout the cell cycle?

False

The cleavage furrow always forms in the middle of the cell.

False

The loading of the origin recognitions complexes (ORCs) is triggered by S-Cdk. True or false?

False

The phenotype of an organism reflects all of the alleles carried by that individual

False

True or False: Centrosomes are special regions of chromosomes that link a pair of sister chromatids

False

Which of the following does not occur during M phase in animal cells?

Growth of the cell

Which of the following statements about the experiment diagrammed in FigureQ19-38 is true?

If you crossed all the round-seeded pea plants from the F2 generation with true-breeding wrinkle-seeded pea plants, you would get more round-seeded pea plants in the next generation than if you crossed all the round-seeded pea plants from the F1 generation with true-breeding wrinkle- seeded pea plants.

If you crossed the round-seeded plants obtained in the F1 generation with a true-breeding strain of round-seeded plants, how many wrinkle-seeded plants wouldyou expect to obtain in the next generation?

None

Which of the following could be considered a true-breeding strain for the seed-shape phenotype? (See Figure Q19-38.)

all of the wrinkle-seeded plants produced in the F2 generation

Which of the following precede the re-formation of the nuclear envelope during M phase in animal cells?

assembly of the contractile ring

In which phase of the cell cycle do cells check to determine whether the DNA is fully and correctly replicated?

at the end of G2

During sexual reproduction, novel mixtures of alleles are generated. This is because

during meiosis, the segregation of homologs is random such that different gametes end up with different alleles of each gene.

Mitogens are

extracellular signals that induce mitosis and cell division

The phosphorylated retinoblastoma protein allows cells to enter the cell cycle by

Releasing the transcription regulators needed to the transcription of genes required for entry into S phase

Sister chromatid separation occurs because ______ are destroyed by the APC/C

Securins

Conditional alleles are mutant gene versions that encode proteins that can function normally at the permissive condition but are defective at the restrictive condition: one commonly used condition is temperature. Conditional alleles are especially useful to geneticists because they permit the study of essential genes At the permissive temperature the organism lives normally. When the organism is shifted to the non- permissive temperature, the effect of inactivating the gene can be studied_ Which of the three types of mutations shown in below is most likely to lead to conditional allele?

Single nucleotide substitution

Apoptosis can be promoted by the release of cytochrome c from the mitochondria

T

Apoptosis differs from necrosis in that necrosis causes cells to swell and burst, whereas apoptotic cells shrink and condense.

T

Mitochondrion actively participates in animal apoptosis

T

Programmed cell death occurs by means of an intracellular suicide program

T

an apoptotic animal cell is chemotatic And thus leading to massive cell and tissue death

T

What would happen if a cell lacked a protein required for a checkpoint mechanism that operates in G2?

The cell would enter M phase under conditions when normal cells would not

Imagine meiosis in a diploid organism that only has a single chromosome. Like most diploid organisms, it received one copy of this chromosome from each of its parents and the two homologs are genetically distinct. If only a single homologous recombination event occurs during meiosis, which of the following choices below correctly describes the four gametes formed.

Two of the gametes will have chromosomes identical to the chromosomes found in the original diploid cell, while two of the gametes will have chromosomes that are different.

Which of the following statements about the round-seeded pea plants obtained inthe F2 generation is false? (See Figure Q19-38.)

We expect 25% of these plants to be homozygous for the seed-shape allele.

Finding co-inheritance of an SNP variant and a disease tells scientists that:

a gene important for causing the disease is linked to the SNP

Somatic cells leave no progeny

True

True or False: G2 phase is a period of rapid cell growth and protein synthesis during which the cell prepares itself for mitosis. It ends when a threshold level of active cyclin B/Cdk1 complex has been reached

True

another name for the fertilized egg Cell is the zygote

True

Levels of Cdk activity change during the cell cycle, in part becaUse

cyclin concentrations change during the cycle (because of gene expression or cyclin degradation); Cdk can be phosphorylated or dephosphorylated; the levels of Cdk inhibitors change.

A cell with nuclear lamins that cannot be phosphorylated in M phase will be unable to

disassemble its nuclear lamina at prometaphase

Progression through the cell cycle requires a cyclin to bind to a Cdk because

the binding of a cyclin to Cdk is required for Cdk enzymatic activitY

If you crossed the round-seeded plants obtained in the F1 generation with a true-breeding strain of wrinkle-seeded plants, how many round-seeded plants wouldyou expect to obtain in the next generation?

50%

In the absence of recombination, how many genetically different types of gamete can an organism with six homologous chromosome pairs produce?

64

The formation of a bivalve that during meiosis ensures that

All four sisters chromatids remain together until the cell is ready to divide

Which of the following reasons was essential for Mendel's law of independentassortment?

All the traits that Mendel examined involved genes that did not display linkage.

Which event does NOT usually occur during interphase?

The nuclear envelope breaks down; Duplicated chromosomes pull apart

Which of the following reasons was essential for Mendel to disprove the theory ofblended inheritance?

The traits that Mendel examined involved an allele that was dominant and an allele that was recessive.

There are organisms that go through meiosis but do not undergo recombination when forming haploid gametes. Which of the following statements correctly describes the gametes produced by such an organism. (Assume that these organisms are diploid, that each of the two homologous chromosomes are genetically distinct as typically found in the wild, and that these organisms have more than one chromosome.)

This organism could potentially produce 2n genetically distinct gametes, where n is its haploid number of chromosomes.

A single nondisjunction event during meiosis will result the production of two normal gametes if it occurs during meiosis II.

True

After the first meiotic cell division cells are produced that contain the same number of chromosomes as somatic cells.

True

During meiosis, the paternal chromosomes pair with the maternal chromosomes before lining up at the metaphase plate.

True

Cells in the G0 state

have entered this arrest state from G1 and do not divide, but they can reenter the cell cycle

Disassembly of the nuclear envelope

must occur for kinetochore microtubules to form in animal cells

Cytokinesis in animal cells

requires ATP

The concentration of mitotic cyclin (M cyclin)

rises gradually during G2 and falls toward the end of M phase as a result of ubiquitylation and degradatiOn

Which of the following statements about genome-wide association studies (GWAS) is false?

studies using GWAS only examine SNPs that occur very rarely (<0.001%) in the population, as those SNPs are most likely to cause disease